The Shore Below the New Sea Wall (Part 2)

The rock ledges below the new sea wall at Church Cliffs in Lyme Regis, Dorset, are the upper strata of the Blue Lias limestone. The natural limestone ledges and the smooth artificial substrate of the concrete sea wall, provide a home for numerous seashore creatures like limpets, winkles, and top shells as well as many commonly attached red, green and brown seaweeds, and encrusting calcareous algae (pink Lithamnion). The brown substance sticking to a lot of limpet shells is also an encrusting seaweed (probably Brown Limpet Paint Ralfsia verrucosa).

Multitudes of small holes penetrating the rocks are the often-occupied burrows of small marine polychaete worms like the Polydora species. Occasional drifts of sandy ripples coating the stone are punctured by largish round holes where bivalved burrowing piddocks living in the rocks below have squirted jets of water from their exhalent siphons and cleared the sand away.

It is interesting to see that the seashore life is equally at home on the old concrete footings from the defunct breakwaters as it is on the limestone.

Thank you, Linda. The biggest difference as far as I can see, since the construction of the new sea wall and the removal of the breakwaters, is the disappearance of the pebbles and cobbles that used to overlie the rock ledges high on the shore. Since mobile substrates such as pebbles discourage most types of communities from settling, their absence has opened up new areas of stable habitat which organisms can exploit and occupy.

Thank you, John. I think perhaps my eye for smaller details has developed because it was necessary to be observant during my former working life, and essential for understanding the phenomena of the natural world.